Bridged Polysilsesquioxane Research Articles

Highly Luminescent and Stable Perovskite Quantum Dots Films for Light‐Emitting Devices and Information Encryption

AbstractThe inherent flexibility and excellent mechanical strength of lead halide perovskite quantum dots (LHP‐QDs) films have attracted much attention in the fields of flexible lighting, displays, non‐planar x‐ray imaging, and wearable optoelectronics. Unfortunately, the complicated synthesis process and poor stability limit its practical applications, hence there is an urgent need to develop a feasible fabrication process for films to attain high device performance. Herein, a molecular level hybridization of bridged polysilsesquioxane (BPSQ) is designed as matrix to harvest both flexibility of organics and stability of inorganics, resulting in improved interfacial compatibility between the CsPbBr3 QDs and the matrix through chemical bond anchoring. The CsPbBr3@3‐aminopropyl‐triethoxysilane (APTES)@BPSQ films showcase bright narrow‐band photoluminescence, with a photoluminescence quantum yield of 61% and a half‐peak full width at half maximum of <17 nm. Notably, these films demonstrate excellent environmental stability, UV resistance, water stability (experiencing only an 18% decrease in luminescence intensity after 168 h of water immersion), and high‐temperature stability (withstanding temperatures up to 500 K). Furthermore, white light‐emitting diodes (WLEDs) and anti‐counterfeiting patterns have been fabricated using CsPbBr3@APTES@BPSQ, highlighting their wide application potential in flexible light‐emitting devices and information encryption.

Polymer-derived silicon oxycarbonitride bowls with hollow structures and hetero-nanodomains for electromagnetic wave absorption

The surface concave structure and inner cavity improve impedance matching and multiple reflections/scattering. The hetero-nanodomains create dipolar and interfacial polarizations.

Fabrication and microstructure evolution of monolithic bridged polysilsesquioxane-derived SiC ceramic aerogels

SiC aerogels are representative high-temperature ceramic aerogels that have demonstrated extensive potential utility in the thermal insulation field under extreme conditions. Although the efficient fabrication of monolithic and highly crystalline SiC aerogels is crucial, it remains highly challenging. Herein, a one-step pyrolysis strategy of a bridged polysilsesquioxane (BPSi) aerogel precursor is reported. The preceramic BP aerogel was prepared via a sol-gel method followed by vacuum drying, and the subsequent pyrolysis process conveniently converted the BPSi aerogel precursor into a SiC aerogel. This circumvents the need for harsh synthetic conditions, high-cost noble metal catalysts, special drying, and additional calcination processes. Furthermore, a competitive mechanism between the “gas-escape” caused by the volatilization of low molecular compounds and carbothermal reduction reaction, and the “volume-shrinkage” resulting from high-temperature sintering was proposed to explain the evolution of phase composition and pore hierarchy of BPSi-derived ceramic aerogels.

Synthesis of non-spherical bridged polysilsesquioxane particles with controllable morphology

Bridged polysilsesquioxanes (BPS) are promising organic–inorganic hybrid materials with tunable properties and versatile applications. However, the facile synthesis of non-spherical BPS particles still remains a challenge. Herein, non-spherical BPS particles were prepared through a one-step sol-gel method using 1, 2-bis (triethoxysilyl) ethane (BTSE) and vinyltrimethoxysilane (VTMS) as precursors. The catalysis of ammonia was essential in constructing non-spherical BPS particles. With the amount of ammonia increasing, the morphology of BPS particles could range from bowl-like to raspberry-like. Scanning electron microscope (SEM) was used to observe the morphologies and track the growth process of BPS particles. The result of 29Si nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) implied that the inner and surface composition of BPS particles was different and silanol groups existed on the surface. Hence, we proposed a possible formation mechanism in accordance with these results and expected that this work would contribute to the synthesis of desired morphologies of BPS particles in various fields.

Photoresponsive Bridged Polysilsesquioxanes for Protein Immobilization/Controlled Release and Micropatterns.

Protein micropatterning on microfabricated surfaces is a promising technology in applications for biochip microarrays, cell attachment, and biosensors. In the present work, a novel photoresponsive polymer based on light-triggered charge shifting bridged polysilsesquioxane (CBPS) is designed and prepared. The organic bridged units containing a photocleavable group of diethylaminocoumarin-4-yl in CBPS could be cleaved rapidly upon irradiation at 410 nm, resulting in the polymer surface switching from a positive charge to a negative charge property. The photoresponsive behavior of CBPS is studied using FTIR, UV-vis, SEM, fluorescence microscopy, and zeta potential analysis. Proteins are easily immobilized on the polymer surface via electrostatic interactions and released after irradiation as required. Combined with photopatterning techniques, accurate protein micropatterns are fabricated by covering a photomask upon irradiation. A gradient protein pattern is also spatially and temporally controlled by regulating irradiation parameters. This smart photoresponsive polymer surface provides a gentle and straightforward strategy to micropattern charged proteins. Moreover, the photoresponsive polymer holds permitting potential in biomedical applications such as conjugating biomolecules, guiding cell arrays, and resisting bacteria.

Precise Controlled Target Molecule Release through Light-Triggered Charge Reversal Bridged Polysilsesquioxane Nanoparticles.

Precise control of target molecule release time, site, and dosage remains a challenge in controlled release systems. We employed a photoresponsive molecule release system via light-triggered charge reversal nanoparticles to achieve a triggered, stepwise, and precise controlled release platform. This release system was based on photocleavage-bridged polysilsesquioxane nanoparticles which acted as nanocarriers of doxorubicin loaded on the surface via electrostatic interaction. The nanoparticles could reverse into positive charges triggered by 254 nm light irradiation due to the photocleavage of the o-nitrobenzyl bridged segment. The charge reversal property of the nanoparticles could release loaded molecules. Doxorubicin was selected as a positively charged model molecule. The as-prepared nanoparticles with an average size of 124 nm had an acceptable doxorubicin loading content up to 12.8%. The surface charge of the nanoparticles could rapidly reverse from negative (−28.20 mV) to positive (+18.9 mV) upon light irradiation for only 10 min. In vitro release experiments showed a cumulative release up to 96% with continuously enhancing irradiation intensity. By regulating irradiation parameters, precisely controlled drug release was carried out. The typical “stepped” profile could be accurately controlled in an on/off irradiation mode. This approach provides an ideal light-triggered molecule release system for location, timing, and dosage. This updated controlled release system, triggered by near-infrared or infrared light, will have greater potential applications in biomedical technology.

Light controlled release system based on photoresponsive bridged polysilsesquioxane nanocarriers

Light-controlled release system plays an important role in the stimuli-responsive release application, due to light with its efficient controllability and non-contact. By adjusting the light irradiation of intensity, wavelength, time and location, the release behavior of the target molecule, such as the release rate, location and concentrations, can be performed by spatial and temporal control. Bridged polysilsesquioxanes have a -[A-SiO1.5] n -molecular chain structure (A is an organic group) which show good mechanical properties and biocompatibility. Due to the wide designability and tunability of the A organic group, bridged polysilsesquioxane materials with different properties can be prepared. This kind of hybrid inorganic-organic materials have potential application values on stimulus-responsive release, optical sensors and biological imaging. A novel photoresponsive controlled release system based on this material was designed and prepared in the present study. When target molecules are connected to nanocarriers with photoresponsive groups by a covalent bond, the covalently binding tends to affect the characteristics of the target molecules, and the chemical process of preparing the controlled release system is complex. Therefore, a photoresponsive controlled release system with simple preparation process and guaranteed target molecular characteristics is highly desired to be constructed. In the paper, a bridged silane containing 2-nitrobenzyl group (BS) was successfully prepared. First, 2-nitrobenzyl chloroformate was obtained by substitution reaction of 2-nitrobenzyl alcohol and triphosgene. Then, the photoresponsive bridged silane monomer BS was produced from 2-nitrobenzyl chloroformate and bis(trimethoxysilylpropyl)amine. The photoresponsive group 2-nitrobenzyl was covalently connected with the silane through an ester group. The synthesized BS was confirmed by nuclear magnetic resonance spectroscopies (1H NMR, 13C NMR, and 29Si NMR), FTIR and mass spectrometry. UV-vis spectra showed that BS was photoresponsive under 254 nm light. The characteristic absorption peaks of the BS at 300 and 224 nm obviously changed during the period of irradiation. Furthermore, the maximum photoreaction conversion was 70% at the irradiation time of 70 min. Further, photoresponsive bridged polysilsesquioxane nanoparticles (BPS) were prepared from BS using a sol-gel method. The prepared BPS nanoparticles were characterized by SEM and DLS. The results showed that the nanoparticles had a spherical morphology with an average particle size of 127 nm. The UV-vis spectra of BPS in an aqueous solution irradiated over different time testified the photoresponse property of BPS. More importantly, the surface charge of BPS nanoparticles could be reversed from negative (–28.20 mV) to positive (+22.86 mV) triggered by light. Upon irradiation, the secondary amine groups were exposed on the surface of BPS due to the photocleaved reaction of photosensitive groups. And the further protonation of amine groups in the aqueous solution increased the positive property of the surface of BPS. The properties indicated that the light-triggered charge reversal nanoparticles may be promising candidates for controlled drug release system. Doxorubicin (DOX) as a widely used clinical anticancer drug was used to evaluate the concept of charge reversal. It was easily combined on the BPS nanoparticles by electrostatic interaction. The nanoparticles could efficiently load 14.8wt% of DOX. The strategy to prepare drug-loaded nanocarriers is simple, mild and high efficiency. In vitro release results showed that the loaded DOX release rate had positive correlation with irradiation intensity and irradiation time (254 nm). The release behaviors under different laser power (60, 160 and 200 mW/cm2) were performed in PBS buffer (pH 7.4) at 37°C over a period of 16 h. There was no obvious release without light. The loaded DOX release rate increased with the increasing irradiation intensity or irradiation time. The highest release rate was 82.9% under 200 mW/cm2 irradiation over 16 h. Moreover, no sudden release behavior was found for the drug-loaded nanoparticles occurred within 6 h of irradiation. As a result, the drug release process can be precisely controlled by regulating the irradiation time and intensity. The prepared DOX@BPS drug-loaded nanoparticles exhibited good photoresponsive performance.

Bridged polysilsesquioxane membranes for water desalination

Water desalination through a reverse osmosis (RO) membrane is an important technology for producing pure water from seawater. High-performance membrane materials have been extensively developed because these materials are useful as core elements in practical water separation processes. Bridged polysilsesquioxane (PSQ)-derived membranes are promising candidates for robust RO membranes because they exhibit high thermal stability and chlorine resistance compared to conventional aromatic polyamide membranes. This review reports on our recent studies involving the development of RO membranes based on bridged PSQs. Our goal is to attain high water permeance with high salt rejection by optimizing the bridged PSQ structure. We have found that the introduction of hydrophilic and/or rigid bridging units tends to enhance water permeability. The preparation and evaluation of bridged PSQ RO membranes for water desalination based on the effects of the bridge structures are described. The bridged PSQ membranes are typically prepared by using a sol–gel process that involves hydrolysis/condensation of bridged alkoxysilane precursors to form sols followed by coating of the resulting sols and calcination of the coated sols to afford the gel membranes. Because the sol–gel process is a complicated multistep process, the development of a new and simpler process has been pursued. Herein, we summarize the recently introduced interfacial polymerization approach as a new method to readily prepare bridged PSQ RO membranes. Water desalination through a reverse osmosis (RO) membrane is an important technology for producing pure water from seawater. High-performance membrane materials have been extensively developed because these materials are useful as core elements in practical water separation processes. Bridged polysilsesquioxane (PSQ)-derived membranes are promising candidates for robust RO membranes because they exhibit high thermal stability and chlorine resistance compared to conventional aromatic polyamide membranes. This review reports on our recent studies involving the development of RO membranes based on bridged PSQs.

New composites of polydopamine-coated bridged Polysilsesquioxane and Pd Nanoparticles Containing POSS

Spherical bridged polysilsesquioxane (BPS) nanoparticles were prepared by the hydrolysis and condensation reaction of urethane-based BPS monomer made from 1, 4-butanediol and 3-(triethoxysily)propyl isocyanate. Polydopamine (PDA) was coated on the surfaces of BPS by the self-polymerization of dopamine under pure oxygen at room temperature. To create aggregates of Pd nanoparticles on PDA-coated BPS, polyhedral oligomeric silsesquioxane (POSS-NH3+) as a cross-linker was incorporated on the surfaces of PDA-coated BPS. Aggregates of Pd nanoparticles were densely produced on the surfaces of PDA-coated BPS by the mixing of POSS/PDA-coated BPS and palladium (Π) acetate in a methanol solution.

Influence of alkalinity on the synthesis of hierarchical LTA zeolite by using bridged polysilsesquioxane.

The mechanism of formation of hierarchical LTA zeolite involved the methoxyl groups of bridged polysilsesquioxane hydrolyzing into hydroxyl groups. The covalent Si–O–Si bond between silicon hydroxyl in the above solution and other silica sources forms by dehydration, avoiding phase separation. The influence of alkalinity on the synthesis of hierarchical LTA zeolites was investigated by using bridged polysilsesquioxane. XRD patterns indicate the synthesis of sodalite at the same molar composition of the hierarchical LTA zeolites without bridged polysilsesquioxane. The characterization results from TG and DTG revealed that bridged polysilsesquioxane was successfully incorporated into the as-synthesized hierarchical LTA zeolite. N2-adsorption/desorption results proved that mesopores and the porosities of the hierarchical LTA zeolites are adjustable by a change of alkalinity. SEM images indicated that the morphologies of the hierarchical LTA zeolites changed with increasing alkalinity. The hierarchical LTA zeolites showed faster initial exchange rates of Na+ to Mg2+ compared with conventional LTA.

Pore structure control factors of polyamine-bridged polysilsesquioxanes by sol–gel method and their structure-adsorption properties for Au(III)

ABSTRACTA series of bridged polysilsesquioxane (BPS) materials was synthesized by the sol–gel method from 3-chloropropyl trimethoxysilane, diethylenetriamine (DETA) or ethylenediamine. Tetraethyl orthosilicate (TEOS) and/or one of the two templates, hexadecyl trimethyl ammonium bromide (CTAB) or P123, were used in the co-condensation process to construct some of the porous adsorbents. The adsorption of Au(III) was the highest for samples without TEOS, especially for the DETA series with CTAB template. This study elucidates the synthesis and applications of BPS materials.

Fabrication of organic-inorganic bridged polysilsesquioxane (BPS) matrix containing polycarbonate diol (PCD) units for solid polymer electrolytes (SPEs)

ABSTRACTNew type of solid polymer electrolytes (SPEs) were synthesized by polycarbonate diol (PCD)-based bridged polysilsesquioxane (BPS) monomer and lithium bis(trifluoromethane)sulfonimidate (LiTFSI) via the sol-gel process. The ion conductivity of PCD-based BPS matrix was increased from 1.41 × 10−7 to 4.09 × 10−5 ((Ω · cm)−1) according to the amount of lithium salts at room temperature. The effect of lithium salts to the ion conductivity is attributed to the homogenous dispersion of lithium salts into the SPEs matrix. The thermal stability of PCD-based BPS matrix is higher than that of PCD oligomer and PCD-based BPS monomer in thermogravimetric analysis (TGA).

Hybrid Nanocomposites of Bridged Polysilsesquioxane Nanoparticles and Polystyrene by Radical Polymerization

티올 그룹을 함유한 구형의 브릿지드 폴리실세스퀴옥세인 나노입자(BPS-SH)는 bis[3-(triethoxysilyl)propyl]-disulfide를 암모니아와 알코올 용매 하에서 가수분해와 축합 반응 후 얻어진 브릿지드 폴리실세스퀴옥세인 나노입자(BPS-S-S)의 환원 반응을 통하여 제조하였다. BPS-SH와 triethylene glycol dimethacrylate(TEGDMA)에 365 nm 파장을 가진 UV를 조사하여 TEGDMA 그룹을 함유한 브릿지드 폴리실세스퀴옥세인 나노입자(BPS-TEGDMA)를 얻을 수 있었다. 합성된 BPS 나노입자는 구형의 형태를 띠고, 평균 입자크기는 200-300 nm를 나타내었다. 이렇게 얻어진 BPS-TEGDMA와 스티렌 단량체를 AIBN 개시제 하에서 중합시켜 BPS 나노입자에 폴리스티렌을 성장시킨 새로운 유-무기 복합체(BPS-TEGDMA/PS)를 합성하였다. BPS 나노입자 표면은 폴리스티렌으로 덮여있어 소수성이 증가하는 것을 확인할 수 있었다. 제조된 BPS-TEGDMA/PS의 구조 및 표면 분석은 FTIR, TGA, SEM, TEM과 같은 다양한 분석장비를 이용하여 수행하였다.

New Water Vapor Barrier Film Based on Lamellar Aliphatic-Monoamine-Bridged Polysilsesquioxane.

Siloxane-based hybrid lamellar materials with ordered nanostructure units paralleling to the substrate have been widely used for water vapor barrier. However, it is very difficult to control the orientation of the lamellar units at molecular level. In this Research Article, a new lamellar bridged polysilsesquioxane (BPSQ) film, whose voids between lamellae were filled by pendant alkyl chains in the organic bridge, was prepared via the stoichiometric reaction between 3-glycidoxypropyltrimethoxysilane and aliphatic monoamine at 60 °C without catalyst. Experimental evidence obtained from FT-IR, MS, NMR, and GIXRD techniques suggested that the as-prepared BPSQ films were constructed by lamellar units with disordered orientation. Nonetheless, they possessed satisfactory water vapor barrier performance for potassium dihydrogen phosphate (KDP) and deuterated potassium dihydrogen phosphate (DKDP) optical crystals, and the water vapor transmission rate through BPSQ film with thickness of 25 μm was as low as 20.3 g·m(-2)·d(-1). Those results proved that filling the voids between molecular lamellae with alkyl chains greatly weakened the effect of lamellar unit orientation on the vapor barrier property of BPSQ film.

Synthesis and Characterization of Bridged Polysilsesquioxane Nanoparticles and Their Nanocomposites with Polycaprolactone by UV Irradiation

Spherical bridged polysilsesquioxane nanoparticles with thiol groups (BPS-SH) were prepared by the reduction of BPS with disulfide groups after the base-catalyzed hydrolysis and condensation reaction of bis(triethoxysilylpropyl)disulfide. The average size of BPS was around 100∼300 nm. Hydroxyethyl methacrylate (HEMA)-initiated polycaprolactone (PCL) was synthesized by ring-opening polymerization of caprolactone under the co-initiation of HEMA and Sn(Oct)2. New nanocomposites of BPS-SH and HEMA-PCL were fabricated by the photo-induced chemical reaction under a photoradical generator and ultraviolet light. BPS was fully and continuously covered with PCL, which resulted in the rough surface of BPS nanoparticles as well as the connected BPS nanoparticles together.

Controlling nanostructure in periodic mesoporous hexylene-bridged polysilsesquioxanes

Periodic mesoporous bridged polysilsesquioxane (PMBPS) materials are hybrid organic inorganic materials with long range order and porosity between 1–15nm length scales and great promise as adsorbents and chromatographic materials. In this study, we describe the preparation and optimization of a class of PMBPS with hexylene-bridging groups and cubic Pm3n symmetry. These hexylene-PMBPSs were prepared by surfactant templating of the sol–gel polymerization of 1,6-bis(triethoxysilyl)hexane (BESH) with cetyltrimethylammonium bromide (CTAB) and N-(3-trimethylammoniumpropyl)hexadecylammonium dibromide (C16–3–1). Powder X-ray diffraction (XRD) and nitrogen adsorption data were used to ascertain the influence on the mesostructure as a function of monomer concentration and aging duration, and aging temperature.

Deriving bridged polysilsesquioxane xerogels with ≡Si(CH2)3NHP(O)(OC2H5)2 functional groups

The reaction of hydrolytic polycondensation of (C2H5O)3SiC2H4Si(OC2H5)3 [or (C2H5O)3SiC6H4Si(OC2H5)3] and (C2H5O)3Si(CH2)3NHP(O)(OC2H5)2 was used to obtain xerogels containing a phosphine oxide complexing group (0.9–1.4 mmol/g). The presence of this functional group, as well as organic bridges, polysiloxane bonds, noncondensed silanol, and ethoxysilyl groups in the synthesized bridged polysilsesquioxane xerogels, was established using IR spectroscopy and solid-state 1H MAS NMR spectroscopy. The AFM data indicate that the structure of xerogels is similar to that of other materials of this class (conglomerates of aggregates with the size of 35–40 nm); however, all the obtained samples are practically nonporous. They extract ions of neodymium(III) and dysprosium(III) from aqueous solutions (sorption equilibrium is established in 72 h for neodymium and in 24 h for dysprosium). However, some ligand groups remain inaccessible to lanthanide ions. The whole set of the obtained results indicates that the geometrical sizes of a functional group produce a considerable effect on formation of xerogel porous structure and in the case of using bridged alkoxysilanes as structure-forming agents.

New composites of spherical bridged polysilsesquioxanes and aggregates of Pd nanoparticles with POSS via ionic interactions

Spherical bridged polysilsesquioxane (BPS) particles with sulfonic groups (BPS–SO3 −) were prepared by the subsequent reduction and oxidation of BPS with disulfide groups (BPS–S–S) after the hydrolysis and condensation reaction of silane monomers with disulfide groups under ammonia and alcoholic solutions. Spherical aggregates of Pd nanoparticles (Pd–polyhedral oligomeric silsesquioxanes, Pd–POSS) were produced by the mixing of POSS and palladium (II) acetate in methanol solution. The average size of BPS–SO3 − and Pd–POSS was about 200–400 and 30–50 nm, respectively. New BPS–SO3 −/Pd–POSS composites with the shape of BPS–SO3 − covered with Pd–POSS nanoparticles were fabricated by ionic interactions between negatively charged BPS–SO3 − and positively charged Pd–POSS. Pd–POSS nanoparticles were more effectively attached to BPS–SO3 − than BPS–S–S, which resulted from the difference of zeta potential between BPS–SO3 − and BPS–S–S. That is, ionic interactions in BPS–SO3 −/Pd–POSS composites were stronger than those in BPS–S–S/Pd–POSS composites. As the storage time was increased, the precipitation of BPS–SO3 −/Pd–POSS composites in methanol solution resulted from the strong complex between BPS–SO3 − and Pd–POSS unlike BPS–S–S/Pd–POSS composites. New particle composites were characterized by Fourier transform infrared spectra, scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy.

Synthesis and characterization of cubic mesoporous bridged polysilsesquioxane for removing organic pollutants from water

Hexane, octane, phenyl, and biphenyl-bridged bis(triethoxysilyl) precursors were used in synthesizing cubic mesoporous bridged polysilsesquioxane (BPS) copolymers. Structural characterization was carried out by FTIR, small angle XRD, Brunauer–Emmett–Teller-N2 sorption, 1H NMR, and TEM. We successfully synthesized both “rigid” and “soft” 3D cubic mesoporous BPS with high surface area and pore volume, as attested by the comprehensive characterization data. Adsorption of pyrene, phenanthrene, nitrobenzene, and 2,4-dichlorophenol on BPS was greatly affected by adsorbate properties, i.e., Kow, solvation properties and molecular size. Hydrophobic interaction dominantly controlled organic pollutants’ sorption on BPS. Other interactions, e.g., π–π and H-bond interactions, also have effects on sorption as indicated by Kow normalized sorption isotherms. Rigid aromatic BPS (phenyl and biphenyl) showed a higher sorption capacity than soft aliphatic BPS (hexane and octane). A conceptual model was proposed to further explain the phenomena. This study suggests a promising application of cubic mesoporous BPS in wastewater treatment.

Sol–Gel-derived Bridged Polysilsesquioxane as a Hydrogen Peroxide Decomposition Catalyst: Immobilization of a Dimanganese Complex and Its Improved Thermal Stability

Abstract Bridged polysilsesquioxane possessing dimanganese complex moiety, a model complex for catalase, exhibited catalytic activity for the hydrogen peroxide decomposition reaction without any deactivation. The catalytic activity was mostly retained, even after 24-h acid treatment at 80 °C, improving thermal stability after immobilization.